Dio published a
Roman History (,
Rhōmaïkḕ Historía) in 80 books in
Greek, later translated into Latin as the . On the matter of its composition, he writes the following: "I spent ten years in collecting all the achievements of the Romans from the beginning down to the death of
Severus [211 AD], and twelve years more in composing my work. As for subsequent events, they also shall be recorded, down to whatever point it shall be permitted me". The books cover a period of approximately 1,400 years, beginning with the tales from
Roman mythology of the arrival of the legendary
Aeneas in Italy () and the founding of Rome by his descendant
Romulus (753 BC); as well as the historic events of the
republican and
imperial eras through 229 AD. The work is one of only three written Roman sources that document the
British revolt of 60–61 AD led by
Boudica. Until the first century BC, Dio provides only a summary of events; after that period, his accounts become more detailed. Dio's work has often been deprecated as unreliable and lacking any overall political aim. Recently, however, some scholars have re-evaluated his work and have highlighted his complexity and sophisticated political and historical interpretations. Books 22 through 35, which are only sparsely covered by fragments, were already lost by the times of Zonaras. The books that follow, Books 36 through 54, are all nearly complete; they cover the period from 65 BC to 12 BC, or from the eastern campaign of
Pompey and the death of
Mithridates to the death of
Marcus Vipsanius Agrippa. Book 55 contains a considerable gap, while Books 56 through 60 (which cover the period from 9–54 AD) are complete and contain events from the defeat of
Varus in Germany to the death of
Claudius. Of the 20 subsequent books in the series, there remain only fragments and the meager abridgement of
John Xiphilinus, a Byzantine monk from the 11th century sponsored by emperor
Michael VII Doukas. The abridgment of Xiphilinus, as now extant, commences with Book 35 and continues to the end of Book 80. The last book covers the period from 222 to 229 AD (the first half of the reign of
Alexander Severus).
Collections of book fragments The fragments of the first 36 books have been collected in four ways: ;
Fragmenta Valesiana: Fragments that were dispersed throughout various writers, scholiasts, grammarians, and lexicographers, and were collected by
Henri Valois. ;
Fragmenta Peiresciana: Large extracts, found in the section entitled "Of Virtues and Vices", contained in the collection, or portative library, compiled by order of
Constantine VII Porphyrogenitus. The manuscript of this belonged to
Nicolas-Claude Fabri de Peiresc. ;
Fragmenta Ursiniana: The fragments of the first 34 books, preserved in the second section of the same work by Constantine, entitled "Of Embassies". These are known under the name of
Fragmenta Ursiniana, as the manuscript in which they are contained was found in
Sicily by
Fulvio Orsini. ;
Excerpta Vaticana:
Excerpta Vaticana by
Angelo Mai contains fragments of Books 1 to 35 and 61 to 80. Additionally, fragments of an unknown
continuator of Dio (
Anonymus post Dionem), generally identified with the 6th century historian
Peter the Patrician, are included; these date from the time of
Constantine. Other fragments from Dio that are primarily associated with the first 34 books were found by Mai in two Vatican manuscripts; these contain a collection that was compiled by
Maximus Planudes. The annals of
Joannes Zonaras also contain numerous extracts from Dio. ==Content==